Defense spending isn't about missiles, it's about jobs and ultimately Red state welfare.
I guess we can disagree on which states benefit most from the program, but we shouldn't ignore the fact that essentially it is a program that is used to bribe senators and representatives through job spending. It doesn't have a lot to do with what is actually strategically sensible.
[1] https://www.pewtrusts.org/en/research-and-analysis/articles/...
The southeast has cheap land, lots of rainfall, low living costs, and mild winters for year-round operation. Which is also why so many military bases were built there.